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Waist size linked to Type 2 diabetes risk – regardless of BMI

Researchers have demonstrated a strong link between having a large waist circumference and an increased risk of developing Type 2 diabetes, independent of a person’s body mass index (BMI).

In the largest study of its kind, a team led by the Medical Research Council (MRC) Epidemiology Unit, examined data from more than 340,000 people from eight European countries. They found that overweight people with a large waist (defined in this study as over 40 inches/102cm for men and over 34.5 inches/88cm for women) had a similar risk of developing diabetes to those who are clinically obese. This correlation was particularly strong in women.

Greatly increased risk

The research, which is to be published in the journalPLoS Medicine, was based on the EU-funded InterAct study, in which 12,403 people developed Type 2 diabetes over a 15-year follow-up period. The researchers found that 7 per cent of men and 4.4 per cent of women who were overweight (with a BMI between 25 and 29.9kg/m2) and had a large waist went on to develop diabetes within 10 years. This contrasts with those people with normal body weight and a smaller waist circumference, with only 1.2 per cent of men and 0.6 per cent of women developing the condition over the same time period.

Pear-shapes

"Pear-shaped" people (those who are overweight, but with a small waist) had a relatively low risk of developing Type 2 diabetes. However, those with a BMI over 35kg/m2 were at a greatly increased risk, with women in this category 32 times more likely to develop Type 2 diabetes than lean, small-waisted women, and men 22 times more likely to develop the condition than their small-waisted counterparts.

"Allows identification of those at highest risk"

Dr Claudia Langenberg from the MRC Epidemiology Unit said, "We do not suggest replacing BMI as a core health indicator, but our results show that measuring waist size in overweight patients allows doctors to 'zoom in' on this population group and identify those at highest risk of diabetes. These people can then be offered lifestyle advice, which can reduce their risk of developing the disease."

"Important risk factor"

Dr Iain Frame, Director of Research for Diabetes UK, said, "This important study adds to the already strong evidence that having a large waist increases risk of developing Type 2 diabetes and this is why it should be considered as an important risk factor for Type 2 diabetes alongside a person’s BMI.

"This is why the Diabetes UK risk score includes waist size as one of the measures. If you have a large waist then it is a good idea to lose weight, even if you fall within the healthy weight range in terms of your BMI. But I would add a note of caution that many people do not measure their own waists correctly and so can be given a false sense of security if they are not doing it properly."